Carmakers and car enthusiasts both like keeping their knowledge secret and inaccessible, and one way they do it is with confusing acronyms and initializations. Here are the ten grammatical codes that every enthusiast should know, as picked by Jalopnik readers.

Automotive marketers sometimes have to stuff big ideas into small acronyms so the buying public can …
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Welcome back to Answers of the Day — our daily Jalopnik feature where we take the best ten responses from the previous day's Question of the Day and shine it up to show off. It's by you and for you, the Jalopnik readers. Enjoy!

Why it's essential: If you really want to know how much fuel you're using, measure it in gallons per hundred miles (or l/100km for the rest of the world). MPG is actually a measure of how great a car is. The fewer MPG you're getting, the more fun you're having.

Why it's essential: If you see these spelled out next to the stubby thing between your passenger's seat and your driver's seat, you may want to consider getting that fixed with a manual transmission. Remember kids, shifting for yourself is more fun than letting your car do it for you.

Why it's essential: Unless you're driving a real classic around, there's some kind of computer in your car. On-board diagnostics are how your car interacts with all the oily bits that make your car work, and once you can get a look into these diagnostics, you can really master your digitized automobile.

Why it's essential: From the air in your tires, to the force the turbo is working on your engine, air pressure is what makes cars go. When it comes to turbos, it's important to know that more Psi is good, but an ungodly torrent of boost is better.

Why it's essential: DSC, PSM, ESP, whatever you want to call it, it stands for traction control - the electronic brain in your car that keeps the wheels from spinning. The only time you really know you're having fun is when it's switched triumphantly off.

Why it's essential: Sometimes the easiest way is not the fastest way, at least when it comes to engines. Designing and manufacturing a second set of camshafts for a car is not the cheapest thing to do, but it means better breathing and more efficiency for an engine. All you need to know is the more cams you have, the better.

Why it's essential: Add NACA ducts to anything and it will go faster. If the bad guys in Bullitt had NACA ducts, McQueen would be history. If OJ Simpson had NACA ducts on his Bronco, he would've been halfway to Mexico by the time the police got to the highway. Counter-rotating vortices FTW.

Why it's essential: Anti-lock brakes aren't just a great way to keep the guy in the Explorer behind you from plowing into the back of your car in a panic stop, it's also the system that keeps you from going all Heikki Kovaleinen (pictured above) off a cliff when you pile into a corner too fast.

Why it's essential: Though they're more complicated than an open differential, limited slip diffs are what make M3s slide, Silvias drift, and enthusiasts smile. Gearheads have their own kind of LSD, and we all should know what it really is.